Measuring devices have long been used to determine the quantity of fluid, either pneumatic or hydraulic, flowing through a product line. Oftentimes such devices position an orifice-containing plate in such line and measure, with pressure gauges, the pressure differential on opposite sides of such plate. The most appropriate references found during a search performed include the following U.S. Pat. Nos.: 1,456,621; 2,585,290; 2,764,891; 3,321,970; 3,450,164; 3,521,487; and 3,822,592.
The main problem heretofore and presently encountered by prior art devices was and is the inability to provide, over a long period of time, a consistantly accurate measurement. Tolerable error was quite large when energy costs were relatively low. Today and in the future, with the value of oil and gas, for example, ever increasing, inaccuracies can be extremely costly to the seller or buyer of such products. Contributing factors to such inaccuracies have been the inability to provide and maintain the close tolerances required in the fluid passageway and in the orifice alignment. Further when prior art devices have been damaged, such as by abrasion, blockage or the like, the entire measuring device has often had to be replaced. It was to overcome such inaccuracies, and the incumbent expense, that the measuring instrument of this invention was developed.